Isolation and Characterization of Phosphate Solubilizing Bacteria from the Rhizosphere of Faba Bean (Vicia faba L.) in Meknes Region, Morocco

Aims: The objective of this research was to isolate phosphate solubilizing bacteria (PSB) from faba bean rhizosphere in Meknes region and evaluate in vitro their potential for P solubilization as well as their response to the effect of temperature, NaCl, pH and antibiotics.
Study Design: Rhizosphere soil and root nodules from faba bean crop in different sites from Meknes region were collected for the study.
Place and Duration of Study: Department of Biology (Soil & Environment Microbiology Unit) Faculty of Sciences, Moulay Ismail University, Meknes, Morocco; between February and August 2014.
Methodology: Four strains, which retained their P-solubilizing ability after repeated subculturing, from a total of seventy eight isolates were purified, characterized and identified by 16S rRNA gene sequencing.
Results: The isolates were closely related to Pseudomonas cedrina (PT19), Rahnella aquatilis HX2 (P24), Rhizobium nepotum (BSP30) and Rhizobium tibeticum (Rh8). P solubilization index of these isolates ranged from 1, 57-2, 88 in tricalcium phosphate amended National Botanical Research Institute's Phosphate (NBRIP) agar medium. Amount of phosphate solubilized ranged from 62.45 to 119.95 mg P L-1 and drop in pH of the medium ranged from 7 to 3.5. Besides, these strains exhibited resistance to several antibiotics.
Conclusion: The ability of the PSB to solubilize insoluble P and their adaptation to environmental conditions add value to these strains, which could lead to improved inoculants to increase the available phosphorus in the soil for faba bean plant growth and to promote sustainable agriculture.